Internal combustion engine

ABSTRACT

An internal combustion engine ( 1 ) operating in cycles, having:
         a plurality of piston-cylinder units ( 2 ), wherein each piston-cylinder unit ( 2 ) of the plurality of piston-cylinder units ( 2 ) is assigned an ignition device ( 3 ) which can be controlled regarding activation and selection of an ignition timing by an engine control ( 4 ), wherein a piston-cylinder unit ( 2 ), when the ignition device ( 3 ) is activated, produces a power by combustion of a gas-air mixture, which can be transmitted as a torque to a crankshaft ( 5 ) of the internal combustion engine ( 1 )   an intake stroke ( 6 ) and an exhaust stroke ( 7 ), each coupled to the plurality of piston-cylinder units ( 2 )   a supply device ( 8 ) for supplying a gas-air mixture under a boost pressure to the intake stroke ( 6 )   a signal detection device ( 9 ) for acquiring at least one signal which represents a power demand on the internal combustion engine ( 1 ) or from which a power demand on the internal combustion engine ( 1 ) can be calculated   an engine control ( 4 ) for actuating actuators of the internal combustion engine ( 1 ), wherein the at least one signal can be fed to the engine control ( 4 ), and the engine control ( 4 ) is configured in a first operating mode to leave as many ignition devices ( 8 ) deactivated per cycle of the internal combustion engine in dependence on the currently present power demand, that the power of those piston-cylinder units ( 2 ), the ignition devices ( 8 ) of which are activated, results in a torque of the crankshaft ( 5 ) of the internal combustion engine ( 1 ) adapted to the currently present power demand
 
wherein the engine control ( 4 ) is configured to, in a second operating mode, for reducing a risk of deflagration due to unburned gas-air mixture present in the exhaust stroke ( 7 )
   after a first number (N 1 ) of cycles of the internal combustion engine ( 1 ), for a second number (N 2 ) of cycles of the internal combustion engine ( 1 ), to have more piston-cylinder units ( 2 ) produce power per cycle by activating the assigned ignition devices ( 8 ) than would be required for the currently present power demand   after the second number (N 2 ) of cycles of the internal combustion engine ( 1 ), for a third number (N 3 ) of cycles of the internal combustion engine ( 1 ), in dependence on a currently present power demand per cycle of the internal combustion engine ( 1 ), to have so many piston-cylinder units ( 2 ) produce power by activation of the assigned ignition devices ( 8 ) that this results in a torque of the crankshaft ( 5 ) adapted to the currently present power demand.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 17/308,985, entitled“INTERNAL COMBUSTION ENGINE,” filed on May 5, 2021, which issued as U.S.Pat. No. 11,536,210 on Dec. 27, 2022, and which claims benefit andpriority to German Utility Model Application No. DE202020102062.5, filedon Apr. 15, 2020; entitled “Internal Combustion Engine”, which is hereinincorporated by reference in its entirety.

BACKGROUND

The present invention concerns an internal combustion engine operatingin cycles and having the features of the preamble of claim 1, and agenset comprising such an internal combustion engine.

Internal combustion engines require the power of the engine to becontrolled or regulated by means of an engine control. With stationaryinternal combustion engines in particular, it is often undesirable tochange the power by actuating an actuator in the form of closing athrottle valve, because this can reduce the efficiency of the internalcombustion engine. For this reason, control or regulating concepts areimplemented wherein individual, several or all ignition devices of thepiston-cylinder units of an internal combustion engine are temporarilydeactivated, i.e. not ignited. This is known by the term “skip firing”.In particular for the stationary operation of an internal combustionengine, shutdown patterns are disclosed in EP 2 952 712 A1 and EP 2 955355 A1, which are intended to promote a thermally homogeneous state ofthe internal combustion engine.

Mixture-charged internal combustion engines are understood to be thoseengines wherein a gas-air mixture is fed into the combustion chambers ofthe piston-cylinder units (with or without the use of a turbocharger),instead of a separate feed of fuel and air. In the present disclosure,gas is understood to mean a gaseous fuel (also referred to as propellantgas), for instance natural gas.

In the context of the present disclosure, load sheddings refer to eventsin which a relatively large portion of the power demand on the internalcombustion engine disappears for a short period of time.

For instance, load shedding in rotational speed-controlled operation inan isolated grid or during the transition to idle mode corresponds to areduction of the electrical load on the generator and an accompanyingrapid reduction of the load torque on the crankshaft. Due to the drivetorque continuing to exist, this leads to an increase in the rotationalspeed of the crankshaft and all connected rotating parts. In order tokeep the rotational speed within the desired permissible limits, it isnecessary to react as quickly as possible using all available actuatorsof the internal combustion engine which can reduce the drive torque.Besides a favorable influence on boost pressure, fuel-air ratio andignition timing, the skip firing method is an effective measure forquickly reducing the drive torque.

Problems with skip firing can occur in the case of mixture-chargedinternal combustion engines in the context of so-called load sheddings,as in the case of mixture-charged internal combustion engines the supplyof fuel cannot be switched off individually for each combustion chamber.If a large proportion of the power demand is lost during load shedding,a correspondingly large number of piston-cylinder units must remainunignited.

This first of all results in gas-air mixture also reaching thecombustion chambers of those piston-cylinder units that are not ignitedby the assigned ignition device in the context of skip firing.Subsequently, unburned gas-air mixture enters the exhaust stroke, anduncontrolled combustion of the gas-air mixture can occur either still inthe combustion chamber or in parts of the exhaust stroke, which is ofcourse harmful. Another potential negative consequence can be that thegas-air mixture enters a catalyst placed in the exhaust stroke, anddamages or displaces the catalyst. These negative consequences are morelikely and more frequent in the case of load shedding, so that the riskof damage to the machine due to skip firing is particularly high in thecase of load shedding.

Load sheddings can occur, for instance, in internal combustion enginesthat use their crankshaft to drive an electrical generator to produceelectrical energy. Such an arrangement is also referred to as a“genset”.

The object of the present invention is to reduce the risk ofuncontrolled combustion of gas-air mixture in the combustion chambersand/or exhaust stroke of a generic internal combustion engine and ageneric genset when using skip firing to compensate for load sheddingsin mixture-charged internal combustion engines.

This object is solved by an internal combustion engine operating incycles with the features of claim 1 and a genset with such an internalcombustion engine. Advantageous embodiments of the invention are definedin the dependent claims.

BRIEF DESCRIPTION

An internal combustion engine according to the invention comprises:

-   -   a plurality of piston-cylinder units, wherein each        piston-cylinder unit of the plurality of piston-cylinder units        is assigned an ignition device which can be controlled by an        engine control with regard to activation and selection of an        ignition timing, wherein a piston-cylinder unit, when the        ignition device is activated, produces a power by combustion of        a gas-air mixture, which power can be transmitted as a torque to        a crankshaft of the internal combustion engine    -   an intake stroke and an exhaust stroke, each coupled with the        plurality of piston-cylinder units    -   a supply device for supplying a gas-air mixture under a boost        pressure to the intake stroke    -   a signal detection device for acquiring at least one signal        which represents a power demand on the internal combustion        engine or from which a power demand on the internal combustion        engine can be calculated    -   an engine control for controlling actuators of the internal        combustion engine, wherein the at least one signal can be fed to        the engine control, and the engine control is configured in a        first operating mode to leave so many ignition devices        deactivated per cycle of the internal combustion engine        dependent on the power demand currently present that the power        of those piston-cylinder units, whose ignition devices are        activated, results in a torque of the crankshaft of the internal        combustion engine adapted to the power demand currently present    -   an engine control configured to, in a second operating mode,        reduce a risk of deflagration due to unburned gas-air mixture        present in the exhaust stroke        -   after a first number of cycles of the internal combustion            engine, for a second number of cycles of the internal            combustion engine, to have more piston-cylinder units            produce power per cycle by activating the assigned ignition            devices than would be required for the currently present            power demand        -   after the second number of cycles of the internal combustion            engine, for a third number of cycles of the internal            combustion engine, depending on a currently present power            demand, to have so many piston-cylinder units produce power            per cycle of the internal combustion engine by activating            the assigned ignition devices that a torque of the            crankshaft adapted to the currently present power demand is            obtained

In the invention, the unburned gas-air mixture entering the exhauststroke during the first number and the third number of cycles duringskip firing is diluted with exhaust gas during the second number ofcycles, since more gas-air mixture is burned during the second number ofcycles due to (compared to the first number of cycles) an increasednumber of activated ignition devices, and thus more exhaust gas isproduced, which mixes with unburned gas-air mixture in the exhauststroke, so that the probability and frequency of the negativeconsequences of uncontrolled combustion mentioned earlier are reduced.The engine control system can determine how many and which ignitiondevices are to be deactivated in a way known from prior art.

If, during the second number of cycles, the engine control actuates atleast one actuator of the internal combustion engine to reduce the powerproduced by a piston-cylinder unit with the ignition device activated,another advantage of the invention is that the risk of knocking whenload shedding occurs can be reduced.

The term cycle of an internal combustion engine operating in cycles isunderstood to mean an operation cycle of the internal combustion engine,i.e. in the case of a four-stroke engine a rotation of the crankshaftwith a crankshaft angle of 720°, or in the case of a two-stroke engine arotation of the crankshaft with a crankshaft angle of 360°.

As already mentioned, load sheddings are events in which a significantpart of the power demand on the internal combustion engine in rotationalspeed-controlled operation suddenly ceases. In particular, we can speakof load sheddings when more than 30%, preferably 100%, of the powerdemand suddenly ceases.

If with a genset, the electrical energy is fed into a power grid and agrid fault occurs, the energy can no longer be fed into the grid,resulting in a sudden reduction in the power demand on the internalcombustion engine. Another case can occur in so-called island operation,when the electrical energy is not fed into a power grid, but is useddirectly to drive individual or a few consumers (e.g. pumps, etc.). Loadshedding occurs then when one or more of the recipients are suddenlyswitched off.

The ignition devices of the individual piston-cylinder units may includea spark plug protruding into a combustion chamber of the piston-cylinderunit. If the piston-cylinder units have a prechamber and a maincombustion chamber connected to the prechamber, the spark plug can bearranged in the prechamber.

As already mentioned, the invention relates to internal combustionengines which include a supply device coupled to the intake stroke forthe joint supply of gas and air (mixture-charged internal combustionengines). Usually, a mixing device for mixing gas and air is used forthis purpose.

Suspension of an ignition event is, of course, understood to mean thatthe ignition device assigned to a piston-cylinder unit is not activatedor is deactivated while there is gas-air mixture in the combustionchamber and, therefore, ignition of the gas-air mixture would actuallybe necessary for the piston-cylinder unit to produce power.

In one embodiment of the invention, the engine control is configured toswitch from the first operating mode to the second operating mode when apredetermined first criterion is met—preferably when a reduction in thepower demand (and/or its rate of change) exceeds a predetermined limitvalue occurs. Thereby, it is preferably provided that the engine controlis configured to switch from the second operating mode to the firstoperating mode depending on the fulfillment of a predeterminable secondcriterion.

The first criterion can be, for instance, a number of piston-cylinderunits with deactivated ignition device and/or a duration of skip firing.The higher the number of piston-cylinder units with deactivated ignitiondevice and the more cycles the skip firing lasts, the higher is the riskof uncontrolled combustion of gas-air mixture in the exhaust stroke.

The second criterion can be a predetermined number of repetitions of thefirst, second and third number of cycles of the internal combustionengine and/or an increase in the power demand (and/or its rate ofchange)—either measured directly or determined indirectly (e.g. via therotational speed (change)) by a predetermined amount.

In one embodiment of the invention, the engine control is configured torepeat the sequence of the first number, second number, and third numberof cycles of the internal combustion engine in the second operatingmode, for instance until the second criterion discussed in the previousparagraph is met.

In one embodiment of the invention, the engine control is configured toperform, in the second operating mode, a control of at least oneactuator for reducing the power produced by a piston-cylinder unit withactivated ignition device, preferably by reducing the boost pressure inthe intake stroke. This is preferably done by an actuator:

-   -   in the form of a throttle valve arranged in or in front of the        intake stroke, wherein preferably a boost pressure-dependent        limit value is provided for a minimum closed position of the        throttle valve, and it is provided that the throttle valve is        actuated in such a way that a closed position of the throttle        valve remains at or above the limit value, and/or    -   in the form of a blow-by valve of a turbocharger arranged in or        in front of the intake stroke

The load pressure-dependent limit value for a minimum closed position ofthe throttle valve serves to avoid compressor-surge during loadshedding.

In one embodiment of the invention, the engine control system isconfigured to perform a control of at least one actuator for reducingthe power produced by a piston-cylinder unit with activated ignitiondevice in the second operating mode by performing an adjustment of theignition timing to late for at least one of the piston-cylinder unitswith activated ignition device. An adjustment of the ignition timing bya value between 0° and 30°, can for instance be set to a resultingpre-set ignition timing between 0° and 20° and preferably between 0° and10°, before the top dead center of a piston of the piston-cylinder unitconcerned.

In one embodiment of the invention, the engine control system isconfigured to not reduce the power produced by a piston-cylinder unitwith the ignition device activated in the second operating mode for thethird number of cycles of the internal combustion engine. So, in thisembodiment, the power of the piston-cylinder units producing power isnot reduced during the first and third number of cycles of the internalcombustion engine.

In all embodiments of the invention, it may be provided that

-   -   the third number of cycles of the internal combustion engine is        equal to the first number of cycles of the internal combustion        engine and/or    -   the second number of cycles of the internal combustion engine is        smaller than the first number and/or the third number of cycles        of the internal combustion engine.

For instance, the first number can be equal to the third number equal tothree, and the second number can be equal to one. Thereby, it isparticularly preferably provided to actuate all ignition devices duringthe one cycle of the second number.

The second number should always be higher than zero, the first numberand/or the third number could be chosen equal to zero.

In one embodiment of the invention, it is provided that the first numberof cycles of the internal combustion engine and/or the second number ofcycles of the internal combustion engine and/or the number of cycles ofthe internal combustion engine are dependent on the at least one signalfrom the signal detection device.

In one embodiment of the invention, the engine control is configured to,in the second operating mode for the second number of cycles of theinternal combustion engine:

-   -   activate all ignition devices and/or    -   for a plurality, preferably for all, of the piston-cylinder        units with activated ignition device, to adjust the ignition        timing to late.

In all embodiments of the invention, it may be provided that the atleast one signal of the signal detection device is a rotational speedsignal representing a rotational speed of the crankshaft.

The signal detection device can, for instance, be a rotational speedsensor that measures a rotational speed of the crankshaft. However, therotational speed of the crankshaft can also be determined indirectly asknown in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is discussed with reference to thefigures.

FIG. 1 schematically shows an internal combustion engine according tothe invention.

FIG. 2 schematically shows a genset according to the invention.

FIG. 3 schematically shows an exemplary procedure in the case of loadshedding according to a first embodiment.

FIG. 4 schematically shows an exemplary procedure in the case of loadshedding according to a second embodiment.

DETAILED DESCRIPTION

FIG. 1 shows an internal combustion engine 1 according to the inventionwith a plurality of piston-cylinder units 2, wherein eachpiston-cylinder unit 2 is assigned an ignition device 3, which iscontrollable in terms of activation and selection of an ignition timingby an engine control 4, wherein a piston-cylinder unit 2, when theignition device 3 is activated, produces power by combustion of agas-air mixture, which power is transmittable as torque to a crankshaft5 of the internal combustion engine 1.

The internal combustion engine further comprises:

-   -   an intake stroke 6 and an exhaust stroke 7, each coupled to the        plurality of piston-cylinder units 2, wherein an optional        catalyst 15 is arranged in the exhaust stroke 7    -   a supply device 8 for supplying a gas-air mixture under a boost        pressure to the intake stroke 6    -   a signal detection device 9 for acquiring at least one signal        which represents a power demand on the internal combustion        engine 1 or from which a power demand on the internal combustion        engine 1 can be calculated (here, the at least one signal of the        signal detection device 9 is a rotational speed signal        representing a rotational speed n of the crankshaft 5)

The engine control 4 is used to control actuators of the internalcombustion engine 1 (in the context of an open or closed control loop),wherein the at least one signal is feedable to the engine control 4, andthe engine control 4 is configured in a first operating mode to leave somany ignition devices 3 deactivated per cycle of the internal combustionengine 1 depending on the currently present power demand, that the powerof those piston-cylinder units 2, whose ignition devices 3 areactivated, results in a torque of the crankshaft 5 of the internalcombustion engine 1 adapted to the currently present power demand.

The engine control 4 is further configured to, in a second operatingmode for reducing a risk of deflagration due to unburned gas-air mixturepresent in the exhaust stroke 7

-   -   after a first number N1 of cycles of the internal combustion        engine 1, for a second number N2 of cycles of the internal        combustion engine 1, to have more piston-cylinder units 2 per        cycle produce power by activating the assigned ignition devices        3 than would be required for the currently present power demand,        and preferably thereby to control at least one actuator of the        internal combustion engine 1 for reducing the power produced by        a piston-cylinder unit 2 with activated ignition device 3    -   after the second number N2 of cycles of the internal combustion        engine 1, for a third number N3 of cycles of the internal        combustion engine 1, depending on a currently present power        demand, to have so many piston-cylinder units 2 produce power        per cycle of the internal combustion engine 1 by activating the        assigned ignition devices 3 that a torque of the crankshaft 5 is        obtained, which is adapted to the currently present power        demand.

The engine control 4 is further configured to switch from the firstoperating mode to the second operating mode when a predetermined firstcriterion is met—preferably when a change in the power demand and/or itsrate of change exceeds a predetermined limit value. Thereby, it ispreferably provided that the engine control 4 is configured to changefrom the second operating mode to the first operating mode depending onthe fulfillment of a predeterminable second criterion.

The engine control 4 is configured to repeat the sequence of the firstnumber N1, second number N2 and third number N3 of cycles of theinternal combustion engine 1 in the second operating mode.

The engine control system 4 is configured so as to carry out activationof at least one actuator in the second operating mode for reducing thepower produced by a piston-cylinder unit 2 with activated ignitiondevice 3 by lowering the boost pressure in the intake stroke 6, in thiscase by means of an actuator:

-   -   in the form of a throttle valve 10 arranged in or in front of        the intake stroke 6, wherein preferably a boost        pressure-dependent limit value is provided for a minimum closed        position of the throttle valve 10, and it is provided that the        throttle valve 10 is actuated in such a way that a closed        position of the throttle valve 10 remains at or above the limit        value, and/or    -   in the form of a blow-by valve 11 of a turbocharger 12 arranged        in or in front of the intake stroke 6.

The engine control 4 is configured so as to carry out controlling of atleast one actuator for reducing the power produced by a piston-cylinderunit 2 with activated ignition device 3 in the second operating mode, byadjusting the ignition timing to late for at least one of thepiston-cylinder units 2 with activated ignition device 3.

The engine control 4 is configured so as not to reduce, in the secondoperating mode for the third number N3 of cycles of the internalcombustion engine 1, the power produced by a piston-cylinder unit 2 withactivated ignition device 3.

The engine control 4 is configured so as to activate all ignitiondevices 3 in the second operating mode for the second number N2 ofcycles of the internal combustion engine 1, and/or to carry out anadjustment of the ignition timing to late for a plurality, preferablyfor all, of the piston-cylinder units 2 with activated ignition device3.

FIG. 2 shows the internal combustion engine 1 of FIG. 1 as part of agenset 13 with an electrical generator 14 mechanically coupled to thecrankshaft 5 of the internal combustion engine 1. The power demand onthe internal combustion engine 1 results from a load which can beconnected or is connected to the electrical generator 14 via a switchingdevice 16 (shown here in the form of a three-phase power grid 17).

Those events that lie along a line in the different graphs of FIGS. 3and 4 , as viewed vertically, take place at the same time.

FIG. 3 shows how the second operating mode is performed during loadshedding in a first embodiment.

In the top graph “load over time” of FIG. 3 , the power demand on theinternal combustion engine 1 is first at a certain level, and the enginecontrol 4 is in the first operating mode, in which it is configured soas to leave so many ignition devices 3 deactivated per cycle of theinternal combustion engine 1, depending on the power demand currentlypresent, that the power of those piston-cylinder units 2 whose ignitiondevices 3 are activated, results in a torque of the crankshaft 5 of theinternal combustion engine 1 adapted to the power demand currentlypresent. Depending on the power demand, the number of deactivatedignition devices 3 may be zero or greater than zero.

At a certain point in time, the power demand on internal combustionengine 1 suddenly collapses, which is shown in the graph “load overtime” by a sudden reduction of the load.

In the present embodiment, the occurrence of the change in power demandexceeding a predetermined limit value (either measured directly ordetected via an increase in rotational speed) triggers a change in theoperating mode of the engine control 4 from the first operating mode tothe second operating mode.

In this second operating mode, such a number of ignition devices 3 arefirst deactivated for a number N1 of cycles that the increase n inrotational speed is limited (this produces the first maximum in thegraph “rotational speed n over time”). After the number N1 of cycles,the engine control 4 allows more piston-cylinder units 2 per cycle toprovide power by activating the assigned ignition devices 3 for a secondnumber N2 of cycles than would be required for the currently presentpower demand. Although this results in a renewed increase in rotationalspeed n, the risk of uncontrolled deflagration is reduced. The number N3is selected to be zero in this embodiment.

This sequence of N1 cycles and N2 cycles is repeated three times here asan example. Then, two sequences of N1 cycles and N2 cycles follow, ineach of which fewer ignition devices 3 are deactivated during the N1cycles of a sequence than during the N1 cycles of the immediatelypreceding sequence. The numbers N1 and N2 of cycles do not change inthis embodiment. Then the engine control 4 changes again to the firstoperating mode.

The graphs “ignition timing over time”, “actuators over time” and “boostpressure over time” show optional flanking measures (these do not allhave to be carried out together, although this is imaginable) forcontrolling at least one actuator to reduce the power produced by apiston-cylinder unit 2 with activated ignition device 3, in this caseadjusting the ignition timings to late and/or influencing the boostpressure by changing the position of a throttle valve and/or actuating ablow-by valve. Due to the lowering of the boost pressure, the number ofdeactivated ignition devices 3 in the first operating mode before andafter the changes in the power demand can be the same (not mandatory),e.g. equal to zero, since the lower load is taken into account by thelowered boost pressure.

FIG. 4 shows how, in a load shedding in a second embodiment, the secondoperating mode is carried out, wherein here, in contrast to theembodiment of FIG. 3 , the numbers N1 and N2 of cycles are notnecessarily kept constant, but are changed over time, e.g. depending onthe at least one signal of the signal detection device 9.

LIST OF REFERENCE SIGNS

-   -   1 internal combustion engine    -   2 piston-cylinder unit    -   3 ignition device    -   4 engine control    -   5 crankshaft    -   6 intake stroke    -   7 exhaust stroke    -   8 supply device for gas-air mixture    -   9 signal detection device    -   10 throttle valve    -   11 blow-by valve    -   12 turbocharger    -   13 genset    -   14 electrical generator    -   15 catalyst    -   16 switching device    -   17 power grid    -   N₁ first number of cycles    -   N₂ second number of cycles    -   N₃ third number of cycles    -   n crankshaft rotational speed

The invention claimed is:
 1. A system, comprising: a controllerconfigured to control a power output of an internal combustion enginehaving a plurality of combustion chambers associated with a respectiveplurality of piston-cylinder assemblies, wherein the controller isconfigured to: control an ignition to skip firing in at least onecombustion chamber of the plurality of combustion chambers for a firstnumber of cycles; control the ignition to fire in the at least onecombustion chamber of the plurality of combustion chambers for a secondnumber of cycles after the first number of cycles; and control at leastone actuator to reduce a power produced by firing in the at least onecombustion chamber of the plurality of combustion chambers during thesecond number of cycles.
 2. The system of claim 1, wherein thecontroller is configured to control the at least one actuator to reducethe power produced by at least: adjusting an ignition timing to a latesetting for the at least one combustion chamber firing during the secondnumber of cycles.
 3. The system of claim 2, wherein the late setting ofthe ignition timing comprises a value between 0° and 30° before a pistonof the at least one combustion chamber reaches a top dead center (TDC)position.
 4. The system of claim 1, wherein the controller is configuredto control the at least one actuator to reduce the power produced by atleast: lowering a boost pressure in an intake stroke for the at leastone combustion chamber firing during the second number of cycles.
 5. Thesystem of claim 4, wherein lowering the boost pressure in the intakestroke comprises at least partially closing a throttle valve.
 6. Thesystem of claim 4, wherein lowering the boost pressure in the intakestroke comprises at least partially bypassing a turbocharger of theinternal combustion engine.
 7. The system of claim 1, wherein thecontroller is configured to switch operation of the internal combustionengine between a first operating mode and a second operating mode inresponse to a change in a power demand and/or a rate of change in thepower demand exceeding a threshold limit value, wherein the secondoperating mode includes at least a sequence of the first and secondcycles.
 8. The system of claim 1, wherein the controller is configuredto repeat a sequence of the first and second number of cycles.
 9. Thesystem of claim 8, wherein the controller is configured to change thefirst number of cycles and/or the second number of cycles when repeatingthe sequence.
 10. The system of claim 1, wherein the first number ofcycles is greater than the second number of cycles.
 11. The system ofclaim 10, wherein the first number of cycles is three and the secondnumber of cycles is one.
 12. The system of claim 1, wherein, during thesecond number of cycles, the controller is configured to control theignition to fire in a first number of combustion chambers of theplurality of combustion chambers greater than needed to meet a powerdemand, and the controller is configured to control the at least oneactuator to reduce the power produced by the first number of combustionchambers based on the power demand.
 13. The system of claim 12, wherein,during a third number of cycles, the controller is configured to controlthe ignition to fire in a second number of combustion chambers of theplurality of combustion chambers adapted to meet the power demand. 14.The system of claim 13, wherein the controller is configured to notreduce the power produced by firing the second number of combustionchambers during the third number of cycles.
 15. The system of claim 1,comprising the internal combustion engine having the plurality ofpiston-cylinder assemblies.
 16. A method, comprising: controlling apower output of an internal combustion engine having a plurality ofcombustion chambers associated with a respective plurality ofpiston-cylinder assemblies, wherein controlling the power outputcomprises: controlling an ignition to skip firing in at least onecombustion chamber of the plurality of combustion chambers for a firstnumber of cycles; controlling the ignition to fire in the at least onecombustion chamber of the plurality of combustion chambers for a secondnumber of cycles after the first number of cycles; and controlling atleast one actuator to reduce a power produced by firing in the at leastone combustion chamber of the plurality of combustion chambers duringthe second number of cycles.
 17. The method of claim 16, whereincontrolling the at least one actuator to reduce the power produced byfiring comprises: adjusting an ignition timing to a late setting for theat least one combustion chamber firing during the second number ofcycles.
 18. The method of claim 16, wherein controlling the at least oneactuator to reduce the power produced by firing comprises: lowering aboost pressure in an intake stroke for the at least one combustionchamber firing during the second number of cycles.
 19. The method ofclaim 16, wherein controlling the power output comprises switchingoperation of the internal combustion engine between a first operatingmode and a second operating mode in response to a change in a powerdemand and/or a rate of change in the power demand exceeding a thresholdlimit value, wherein the second operating mode includes at least asequence of the first and second cycles.
 20. A system, comprising: aninternal combustion engine having at least one combustion chamberassociated with a respective piston-cylinder assembly; and a controllerconfigured to control a power output of the internal combustion engine,wherein the controller is configured to: control an ignition to skipfiring in the least one combustion chamber for a first number of cycles;control the ignition to fire in the at least one combustion chamber fora second number of cycles after the first number of cycles; and controlat least one actuator to reduce a power produced by firing in the atleast one combustion chamber during the second number of cycles.